Crystalline engineering plastics are used in a broad field of industry, such as electric and electronic parts and automobile parts. In particular, glass fiber-reinforced engineering plastics have been attracting attention in the field requiring high rigidity and high heat distortion temperature. However, in spite of greatly improved mechanical properties, such as impact resistance, and heat resistance, the molded articles obtained from the glass fiber-reinforced engineering plastics have a deteriorated appearance, such as surface smoothness. A further improvement has therefore been demanded particularly for application to the field giving special weight to an appearance of a molded article, such as electrical parts and automobile parts.
It is known that the impact resistance of engineering plastics can be improved by addition of an epoxy group- or acid anhydride group-containing ethylene copolymer. For example, addition of such an impact modifier to polyester resins is disclosed in JP-B-58-47419 and JP-B-59-28223 (the term "JP-B" as used herein means an "examined published Japanese patent application"); that to polyphenylene sulfide resins is disclosed in JP-B-2-382; that to polycarbonate resins is disclosed in JP-B-61-44897; that to polyarylate resins, polyester carbonate resins, and polysulfone resins is disclosed in JP-A-57-123251 (the term "JP-A" as used herein means an "unexamined published Japanese patent application"); and that to polyamide resins is disclosed in JP-B-55-44108.
It is also known that addition of glass fibers to crystalline resins brings about considerable improvements in mechanical properties, such as tensile strength, compression strength, and flexural rigidity, and heat resistance. For example, JP-B-64-5068 proposes a plastic composition comprising a polyester resin, an epoxy group-containing ethylene copolymer, and glass fibers of specific shape, which provides a molded article with an improved appearance. JP-B-64-6665 proposes to subject a molded article prepared by melt molding a composition comprising a polyester resin, an epoxy compound, and glass fibers to a heat treatment at 200.degree. to 280.degree. C. for 20 minutes or more. Further, JP-A-59-152953 proposes a composition comprising a polyphenylene sulfide resin, an epoxy group-containing ethylene copolymer, and glass fibers.
As a result of studies by the inventors, however, it turned out that the molded articles obtained by the above-mentioned conventional techniques show some improvements bull not to a sufficient degree. A further improvement especially in appearance of a molded article is still demanded.